Sensors are employed in a whole range of technological applications including automotive, medical and printing applications to name a few. Such applications require sensors which can operate reliably and reproducible according to specified performance characteristics. For this reason, sensors are normally individually calibrated during production to offset minor deviations in sensor performance resulting from mass production techniques ensuring that measurements can be performed accurately for each and every sensor produced.
Performance of an electronic sensor is dependent on the transducer/material properties and the biasing current or voltage. For example, in the case of infra red (IR) sensors, which have an IR light emitting diode (LED) and an IR detector, the beam intensity from the LED is affected by the forward current (IF), aging of the LED, dust accumulating on the sensor and other factors. Consequently, the actual detected beam intensity for a given reference sensing environment can vary from the specified intensity thereby affecting the sensitivity of the sensor. In order to obtain sensors with the required sensitivity, the biasing forward current for each IR sensor LED can be adjusted or calibrated at the stage of production, as well as later during the sensor lifetime, such that the sensor provides the required or specified output signal for a given reference sensing environment.
Known sensor calibration techniques typically utilize complex calibration apparatus separate from the sensor to perform the necessary sensor calibration. Each individual sensor must therefore be temporarily connected to the calibration apparatus for calibration. Such production requirements therefore lead to increase in sensor manufacturing costs and time.
An alternative calibration technique utilizes a sensor calibration circuit which circuit includes a computer for the purpose of calculating the calibration co-efficient for sensor characterization based on complex algorithms specific to each type of sensor. The calibration apparatus has to be tailored to different types of sensors. Such a technique is both costly and complicated to implement in each individual sensor.
There is a need to provide a system and method of self-calibrating a sensor which can be implemented in a variety of sensors in a cost-effective manner.
The embodiments disclosed herein therefore directly address the shortcomings of conventional calibration systems and methods by providing an effective system and method of self-calibrating sensor that is suitable for many price sensitive applications.